Various retinal analogs will be synthesized, irradiated with monochromatic light, and the various double bond isomers will be separated by high-speed liquid chromotography. After structure determination, the respective pure retinals will be tested for rhodopsin formation with opsin. The synthetic retinals will be tailored so that collectively they will give a clearer definition of the steric and chiral criteria of the opsin binding site and cavity. A C14-labeled retinal derivative capable of affinity binding to nearby amino acid moieties of opsin through the very reactive nitrene will be syntheiszed to acquire further information on the opsin cavity. The mechanism of the photochemical process of bleaching will be studied. We hope to gain additional information on the Schiff base linkage by C13-labeled rhodopsin cmr studies, and by laser Raman and Fourier transform ir measurements. The yellow fluorescent pigment which accumulates in the human eye lens and which may have a direct bearing on senile cataract is also under study.